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The Concept of HLB 



  The term "HLB" was first employed by the lab staff of the Atlas Powder Co. in America.Amphiphilic surfactants are characterized by the hydrophilic-lipophilic balance (HLB): a relative ratio of polar and non-polar groups in the surfactant
This means the balance between the oil soluble and water soluble moieties in a surface active molecule, and is expressed as the "Hydrophile-Liphophile Balance".

  A more oil-soluble emulsifier shows a lower HLB and a more water-soluble emulsifier shows the reverse. HLB is a very useful method in selecting an emulsifier, but it still has several limitations to application for every surfactant.

  The HLB concept is not enough to describe all the characteristics of emulsion.


         Calculation of the HLB number from a mixture of surfactants



  The HLB number of a mixture composed of x% of surfactants of HLB A and y% of surfactants of HLB B is obtained by the following formula.

                                               HLB ( A + B ) = ( Ax + By ) / ( x + y )

  For instance, if 60 wt.% of POE(3) Octyl Phenol of HLB number 8 is mixed with 40 wt.% of POE(5) Nonyl Phenol of HLB number 10, then the HLB number of this mixture becomes 8.8.
Reversely, to make the mixture of HLB number 11 which is composed of POE(15) Nonyl Phenol of HLB number 15 and POE(2) Nonyl Phenol of HLB number 5.5, then one should mix 42 wt.% of POE(2) Nonyl Phenol wuth 58 wt.% of POE(15) Nonyl Phenol.


HLB ca. 1 to 3.5: Antifoams
HLB ca. 3.5 to 8: Water-in-Oil Emulsifiers
HLB ca. 7 to 9: Wetting and spreading agents
HLB ca. 8 to 16: Oil-in-Water Emulsifiers
HLB ca. 13 to 16: Detergents
HLB ca. 15 to 40: Solubilizers

It is useful to correlate the characteristics of surfactants with the properties that are needed to make various heterogenous systems. A common system which is used to do this is the HLB system. The HLB value for a given surfactant is the relative degree to which the surfactant is water soluble or oil soluble. The lower the HLB, value the more lipophilic. The higher the HLB value, the more hydrophilic. I will not go over how these numbers are derived. You can look it up if you like. The range is usually between 1 and 20. Please note the one exception at the bottom of the table.>

HLB Values and the use for those surfactants

1 Antifoaming Agent Oleic Acid
2 Antifoaming Agent Sorbitan Tristearate
3 Antifoaming Agent Glyceryl Monostearate
4 Emulsifying Agent W/O Sorbitan mono-oleate (Span 80)
5 Emulsifying Agent W/O Glyceryl Monostearate
6 Emulsifying Agent W/O Diethylene glycol monolaurate
7 Emulsifying Agent W/O; Wetting ans Spreading Agents {none}
8 Emulsifying Agent W/O; Wetting and Spreading Agents Sorbitan monolaurate (Span 20)
9 Emulsifying Agent O/W; Wetting and Spreading Agents Polyethylene lauryl ether(Brij 30)
10 Emulsifying Agents O/W Methyl Cellulose(Methocel15 cps)
11 Emulsifying Agents O/W Polyoxyethylene monostearate (Myrj 45)
12 Emulsifying Agents O/W Triethanolamine oleate
13 Emulsifying Agents O/W ; Detergents Polyethylene glycol 400 monolaurate
14 Emulsifying Agents O/W ; Detergents (none)
15 Emulsifying Agents O/W ; Detergents Polyoxyethylene sorbitan mono-oleate(Tween 80)
16 Emulsifying Agent O/W ; Detergents: Solubilizing Agents Polyoxyethylene sorbitan monolaurate (Tween 20)
17 Solubilizing Agents Polyoxylene lauryl ether(Brij 35)
18 Solubilizing Agents Sodium oleate
19 Solubilizing Agents None
20 Solubilizing Agents Potassium oleate
40 Everything Sodium Lauryl Sulfate (Tide)

In laboratory we used Sodium Lauryl Sulfate for most experiments. It dissolves in water very well and is a common additive to most heterogenEous systems and to almost all common detergents, shampoo etc. However, when we made the 1% surfactant in mineral oil we used Span 80.